It is becoming more common to use polysilicon fuses in integrated circuits for permanent selection purposes. One use is for permanently replacing a row or column of a memory which has a defective memory element with a redundant row or column. Another use is in array division of a memory in which major portions of the memory array are permanently deselected. In integrated circuit technology the polysilicon fuses are typically selectively opened by having a control transistor act as a switch in series with the polysilicon fuse. A voltage is applied to the polysilicon fuse and if the fuse is to be opened, the transistor is turned on to provide a current path so that current will flow through the fuse. The current must, of course, be sufficient to open the fuse.
The limitations on the current for a given polysilicon fuse are the magnitude of the applied voltage and the current carrying capability of the transistor. For a given transistor its current carrying capability is increased by applying a higher voltage on its control electrode. Techniques exist for doing this. Another technique has been to apply a high voltage signal to the fuse. Each of these techniques has been used separately but not together. In "Equipping a line of memories with spare cells," by Robert Abbot, Kin Kokkonen, Roger I. Kung, and Ronald J. Smith, Electronics, July 28, 1981, pp. 127-130, each technique is used. FIG. 1.a on page 128 shows a high voltage coupled to the control electrode of the series transistor. FIG. 2.b on page 129 shows a high voltage coupled to the control electrode of the series transistor.